1. Field of the Invention
The present invention relates to building elements or members, but more particularly the present invention relates to a composite structural unit, its method of construction, and a method of constructing or assembling the individual units of the present invention so as to form structural arrays such as for example walls, columns, slabs, ceilings and the like.
2. General Background
It is known to form structural building arrays comprised of a plurality of individual units held together in load bearing abutment to one another by means of overall tension members which extend through or otherwise connect all the individual units in a dimension of the assembled structural array. The tension members are constituted generally of iron, steel or like tensile members with externally threaded ends (or like suitable connections) which extend to the ends of the assemblies of the units such as by the use of plates, washers and nuts, or like end bearing connections. The so constructed unit can be tightly drawn together and handled as a complete structural load bearing unit. Such units are useful in the in situ construction of walls, pre-fabrication of walls, floor slabs, arches, beam and column forms, and the like.
Among the advantages offered by such structural units is that there exists no necessity of using grout, mortar, or like conventional connections between the units or rows of units. Thus the structure can be formed with a smooth, dry load bearing joint at any place and transported from that place of assembly to the location of its use as a complete load bearing self contained unit.
Whereas structural units of this type have generally attempted to solve the problem of providing a structurally sound unit which can be assembled and transported, or in fact assembled at the job site without the use of grout, and attentive labor, a significant deficiency nonetheless exists in the use of such structure units.
One problem which arises with structural units which are so connected in the prior art, is that point stresses often develop at the joints or faces of the units where these members are in abutment, these stress points often being effected after construction when the applied load is manifested. The points of strain set up within the units often cause chipping, cracking, or in fact fracture or failure. Such flaws can at least create an unsightly appearance and worse can result in a threatened stability and utility of the structure itself.
A further problem seen with many prior art structural units is that they require a substantial amount of initial bracing and secondary support to the arrays or individual building units themselves during construction and prior to the application of the tension members to the structure. Such a need for secondary support is time consuming, labor wasting, and expensive. Oftentimes, without the use of heavy construction equipment and construction crews, this type of secondary structural support is out of the question.
Some other prior art units are restricted to a single structural array by their very nature, and cannot be combined into several different forms as may be desired by the individual who is constructing a specific planned building.
It is accordingly an object of the present invention to provide a new and novel structural building unit wherein a structural core to the building unit is provided, having load-distributing surfaces thereon to which point stresses can be applied without significant damage.
Another object of the present invention is to provide a structural building unit which is particularly useful in structural concrete applications, such as reinforced concrete, poststressed concrete, concrete shells, and architectural applications.
A further object of the present invention is to provide a means to more evenly distribute the load stress to the joints of abutting individual structural members without the problem of fracture or cracking.
A further and more specific object of the present invention is to provide structural building units of such character which do not require the use of mortar to hold the units together and which have particular utility in the construction on site or offsite of structural arrays formed from a plurality of individual structural units such as concrete walls, floor slabs, arches, beams, columns, and the like.
A further object of the present invention is to provide a composite structural unit which is provided with means for attaching it to other like units in order to form an array, with the connection means therebetween being the only structural connection necessary in order to form a final and complete structural bond with the individual unit to the array to which it is being attached during construction itself--secondary structures and bracing being unnecessary.
Another object of the present invention is to provide a method of construction of a composite structural unit, which constructed unit requires no additional milling, filing or like refinement after its casting.
These objects and others are achieved in accordance with the present invention embodying an apparatus, or structural building unit, comprised of a inner structural material and there being provided thereon outer load-distributing surfaces to which connection means can be attached without the problem of point stresses creating cracks, chips, or the like.
3. Prior Art
The prior art discloses a number of patents which have been issued on various building systems which attempt to provide a final array of individual building units in order to form walls, ceilings, slabs and the like. A listing of some prior art systems which have been patented is listed in the following table.
______________________________________ Prior Art Patents U.S. Pat. No. Inventor(s) Issue Date ______________________________________ Re. 27,785 H. Kobayashi Oct. 16, 1973 2,102,447 D. D. Whitacre Dec. 14, 1937 2,684,589 A. Perreton July 27, 1954 2,929,236 H. W. Steward et al Mar. 22, 1960 3,145,502 D. Rubenstein Aug. 25, 1964 3,173,226 A. Solnick Mar. 16, 1965 3,260,025 C. Van Der Lely July 12, 1966 3,378,969 G. K. Larger Apr. 23, 1968 ______________________________________
Many of the devices or systems of the prior art which have been patented provide various drawbacks in their attempt to solve the aforementioned problems, to which problems the present invention is directed and which drawbacks and problems are solved by the present invention over the prior art.
U.S. Pat. No. 2,102,447 by Donald D. Whitacre provides a structural building system wherein there is the necessity to grind the contact surfaces between individual structural units prior to assembly. The present invention does not require the grinding or milling of the surfaces of the individual structural units prior to their use, but rather provides a method of construction by which the contact surfaces of the individual units are by their nature perfectly flat and aligned as is required before their use in forming an array.
The present invention provides a significant advantage over the prior art in that there is no necessity of the use of secondary structures or supplemental structures in order to support the array prior to the application of the tensioning members thereto. In the method of constructing the arrays of the present invention, the tension is applied with the addition of each structural unit and such tension member holds that individual structural unit in place without the use of secondary structures, secondary bars, or secondary supports in order to hold the unit until the entire structural unit can be tensioned. The Kobayashi patent, U.S. Pat. No. Re. 27,785 provides the use of such a supplemental structure until the concrete hardens. Such a device requires a secondary structure until the curing time of concrete gives it the desired strength.
U.S. Pat. No. 3,173,226 issued to Abraham Solnick requires the use of extra supportive framework.
In contrast to U.S. Pat. No. 3,145,502 issued to D. Rubenstein, in the present case of plates or surfaces made of plastic, the surface, if formed after the initial molding, is on the abutting surfaces not on the facing surfaces as in the Rubenstein patent.
The present invention does not require a complex system of rods which can only be stressed after an entire row of units is laid, such as is taught in the Perreton patent, U.S. Pat. No. 2,684,589.
U.S. Pat. No. 3,260,025, issued to C. Van Der Lely discloses the use of facings which are formed of a plastic material to make a seal. In the '025 patent, the object is to seal, not to distribute the load evenly over the contact surface as is the case with the present invention. The object of the present invention is to distribute the load and hence the facing material has different characteristics.
The rods with the present invention are not made continuous throughout the entire span as in the devices of the prior art, and do not transmit unequal loads with expansion and contraction effects of rods throughout a dimension of the entire structure.
Also a specific object is to provide a method of assembling the units whereby one unit is placed in position and means of applying compressive force to keep it in place is applied to that unit suitably by the application of tension to rods one end of which is anchored on a face of a unit already in place, that face being other than the one abutting the unit just positioned and the other end of the rod being attached to a face of the unit just positioned which is not identical to the abutting face of the unit just positioned.